It is best to take a snapshot when no applications in the virtual machine are sending transactions to other computers. The potential for problems is greatest if the virtual machine is sending transactions to or receiving transactions from another computer, especially in a production environment.

VMware recommends that you do not take a snapshot under the following conditions.

When the virtual machine is downloading a file from a server on the network. After you take the snapshot, the virtual machine continues downloading the file, transmitting its progress to the server. If you revert to the snapshot, transmission between the virtual machine and the server is confused, and the file transfer fails.

When an application in the virtual machine is sending a transaction to a database on a separate machine. If you revert to that snapshot, especially if you revert after the transaction starts but before it is committed, the database might become corrupted.